Abrasive testing machine



Sept. 1, 1931. H. H. LA VERCOMBE 1,321,159

' ABRASIVE' TESTING MACHINE I;

Filed Aug. 28, 1925 4 Sheets-Sheet 1 ymwmze Sept. 1, 1931. H. H. LAVERCOMBE 3 3 ABRASIVE TESTING MACHINE Filed Aug. 28, 1925 4 Sheets-Sheet2 abtorwuja.

Sept. 1, 1931. H. H. LA VERCOMBE ABRASIVE TESTING MACHINE 4 Sheets-Sheet5 Filed Aug. 28, 1925 gnuento'a:

P 1931- I H. H. LA VERCOMBE ,821,169

ABRASIVE TESTING MACHINE Filed Aug. 28, 1925 4 Sheets-Sheet 4 iiilm 55 IQ) 5/ mnmuunnum 5% 5o 3 nuanf 01 II IIHIIHW Patented Sept. 1, 1931UNITED STATES PATENT OFFICE HARLEY H. LA VERCOMBE, OF DETROTT, MICHIGAN,ASSIGNOR TO ABRASIVE ENGI- NEERIN G CORPORATION, OF DETROIT, MICHIGAN, ACORPORATION OF MICHIGAN ABRASIVE TESTING MACHINE- Application filedAugust 28, 1925. Serial No. 52,974.

This invention relates to machines for testing grinding wheels to securedefinite data as to their wearing and abrasive qualities so that theiradaptability to different classes of work may be properly ascertained.

These qualities are not necessarily dependent upon the size, nature orsharpness of the abrasive material itself, but are usually dependent toa'considerable extent upon the manner in which the grains of suchmaterial are supported, it being understood that the matrix or binder bywhich the said grains are held together may vary considerably and thusalter or influence the cutting qualities of the abrasive materialitself, as Well as the ability of the material to withstand wear.

Devices have been suggested from time to time in the form of machinesadapted to subject a test piece of steel, or other material, to theaction of a stone so that the effect of the stone on the material andthe effect of the material on the stone may be observed, and a gradingof the stone as to its abrasive and Wearing qualities arrived at.

For example, the machines described in United States Letters Patentsgranted to me, Nos. 1,435,314, dated November 14:, 1922, and 1,446,977,dated February 27, 1923, are of this type.

The present invention has for its object to effect still furtherimprovements over the machines hitherto known, whereby the grad ing ofgrinding wheels according to abrasive andwearing qualities may be muchmore closely determined.

To this end the said invention further aims in such a machine to ensurea constant peripheral speed of the grinding surface irrespective of thecircumference of the grinding wheel being testedand the wear of thestone or ofthe test piece, wherefore provision is made for the rotatingof a stone at a speed inversely proportional to its diameter.

The invention has as a further object to provide .for the determining ofuniformity of wearing quality in a wheel whereby uneven wear thereof maybe readily detected, and the extent of such uneven wear ascertained;still further objects being to provide for variation of the pressure ofthe test piece on the grinding wheel, as well as providing a method ofapplying pressure to the test piece without materially increasing'theload on the bearings in which the spindle carrying the test piece ismounted.

Still further objects subsidiary to or resulting from the aforesaidobjects, or from the construction or operation of the invention as itmay be carried into effect, will become apparent as the said inventionis hereinafter further disclosed.

In carrying the invention into effect I may provide a testing machinewith a horizontally mounted and vertically adjustable grinding wheelarbor adapted for thereception of a wheel to be tested, and a verticalrotary spindle positioned and adapted to support a test piece such as ofsteel in contact with the top. of a wheel mounted on said arbor, saidspindle being vertically movable and weighted so that the test piecewill rest on the periphery of the said grinding wheel with a definitepressure, driving means effecting the rotation of said spindle and,through suitable gearing, the rotation of a friction pinion verticallymovable over the face of a friction disk carried by said grindingwheelarbor, whereby, upon the raising of said arbor to bring a grinding wheelinto contact with the test piece, said pinion approaches the axis ofsaid disk to an extent governed by the diameter of the wheel; and thespeed of the arbor is accordingly inversely proportional to suchdiameter. Means are provided for determining the number of revolutionsmade by said pinion or said spindle and for throwing the machine out ofoperation upon a predetermined number of revolutions being attained.

All of which is more particularly described and ascertained hereinafter,by way of example, having reference to the accompanying drawings,wherein Figure 1 is a perspective view of an abrasive testing machineembodying my improvements;

Figure 2 is a side elevation of the same, partly in section and partlybroken away;

Figure 3 is a fragmentary sectional detail view taken on the line300-300, Figure 2;

Figure 4 is a plan of the upper portion of the machine, and

Figure is a plan view of the machine with the upper cover plate removed.

Similar characters of reference indicate similar parts in the severalfigures of the drawings, and Figure 1 is drawn to a smaller scale thanthe remaining figures.

The body structure or pedestal 1 of'the machine illustrated is shown ashaving mounted thereon an upper structure 2 in which the driving andgear mechanism is arranged, and on the said pedestal 1 is a verticallyslidable bearing member 3 which is adjustable in its vertical movementby means of a hand wheel 4 threaded onto a fixed feedscrew 5 whichextends upwardly from the base of the pedestal through a boss 6 on thelower part of the said slidable bearing member 3. In this hearing memberor slide is mounted a horizontal grinding wheel arbor 7 adapted toreceive a grinding wheel 8 which may be secured thereon in anyconvenient manner such as by the usual plate 9, collar 10 and securingnut 11. On the opposite end of the said arbor is a friction disk 12 ofsubstantial diameter.

The said upper structure 2 is shown as being in the form of a gearhousing and also forms the housing for atest cup spindle 13, the upperend of the said structure 2 being closed by a cover plate 14 whichsupports a jack shaft 15 upon which is mounted a driving pulley 16 and ajack shaft pulley 17 which, through a belt 18, drives a countershaftpulley 19 mounted on a spindle 20 extending outwardly of the spindlehousing.

The said spindle 13 is vertically slidable in and rotatable with asleeve 21 which is provided with an operating pulley 22 over which abelt 23 extends guided by idler pulleys 24 and 25, and on the lower endof the said sleeve 2]. is mounted a worm 26 which meshes with a wormwheel 27 mounted on a shaft 28 extending transversely of the gearhousing. This shaft also carries a sprocket wheel 29 which, through theme dium of a chain 30 and sprocket wheel 31, effects the rotation of afurther shaft 32 mounted in the said housing and the conse quentrotation of a bevel gear 33 also mounted on the said shaft 32.

The gear 33 is housed in the upper end of a hollow arm 34swingablymounted on the said shaft 32, which extends outwardly of thestructure 2 for that purpose, and 35 is a rotary spindle journaled inthe said arm and provided at its upper end with a bevel gear 36ineshingwith'the aforesaid bevel gear 33, and at its lower end with a frictionwheel 37 which engages the face of the friction disk 12 under theinfluence of a weight 38 which exerts pressure of the friction wheel 37against the disk 12.

It will be apparent that in this way the grinding wheel arbor 7 isrotated at the same time as the test cup spindle 13, provided that thefriction wheel 37 and disk 12 are in contact, although the arm 34 may beswung outwardly of the said disk 12 against the resistance of a spring39 situated between the gear housing and a stop 40 carried by aprojection 41 on the upper part of the arm. The stop 40 may beadjustable, as by being in the form of a nut mounted upon a threaded rod42, so that the pressure of the spring may be varied. This arrangementpermits of adjustment of the pressure of the wheel 37 against the disk12.

The testing of grindstones with this device is effected by bringing intocontact with the periphery of the grinding wheel a test piece of steelor other suitable material which I prefer to provide in the form of aninverted test cup, such as 43, secured on the lower end of the test cupspindle 13 by a nut 44, this cup being rotated in contact with theperipheryof the wheel when the machine is in operation and the grindingwheel rotated at the same time by the friction wheel 37 and the disk 12.

Upon the mounting of the grinding wheel to betested on the arbor, theslide 3 is then raised by the operation of the hand wheel 4 until theperiphery of the wheel engages the test piece and raises the sametogether with the spindle 13 to a suflicient extent to ensure a fullpressure of the test piece upon the grinding wheel, this pressure beingdetermined by the application of weights 45 to a member 46 preferablypointed at 47 at its lower end which rests upon the upper end of thespindle 13. The member 46 is threaded at 460 for adjustment in asupporting member 48 extending above the said test cup spindle.

When the grindstone is raised into contact with the test cup the disk 12is also raised as will be obvious, and it will be read ily understoodthat the smaller the diameter of the grindstone, the higher it is necessary to lift the disk 12, and the closer the friction wheel 37approaches the axis of the i said disk. Therefore, the smaller the diameter of the grinding wheel the faster it will be rotated, so that theperipheral speed of the grinding wheel will be practically the same.irrespective of its size. This enables grinding wheels of differentsizes to be tested to all intents and purposes under precisely the samecutting conditions, and two grinding wheels of equal abrasive qualityshould therefore effect an equal wear of the test cup in a test carriedover equal periods of operation of the machine, irrespective ofsubstantial differences in the diameter of the grindstones.

In orderto make proper comparisons of the abrasive qualities of grindingwheels and to .ascertain definitely the amountofmaterial ground from thetest cup for a given number of feet of grinding surface applied to thetest cup, indicating and timing means through the gear housing, and anarm swingably mounted on the said housing at 51 and provided at itsouter end with a pawl 52 engaging peripheral teeth of a dial plate 53 sothat upon each revolution of the worm wheel 27 the cam will actuate thesaid pawl 52 against the yielding resistance of a pawl spring 54 andeffect partial rotation of the said dial plate to the extent of thepitch of its peripheral teeth. The dial plate is provided on its innerside with a pin or projection 55, and 56 is a dial pointer indicatingthe position of the said pin relative to trip member 57 hingedly carriedby the end of the downwardly depending arm 58 of a bell crank leverwhich is fulcrumed at 59 to the cover plate of the gear housing. Theupper arm 60 of the bell crank lever is forked and engages the undersideof a collar or annular projection 61 on the test cup I spindle.

The trip member 57 rests upon a stop 62 and is provided with a shoulder63 with which the said stop engages, 64 being a spring tending to effectthe movement of the arm 58 of the bell crank lever away from the dialplate and to thereby effect the raising of the upper member 60 of the abell crank lever, this tendency of the spring 64 being rest-rainedduring the operation of the machine by the engagement of the said stop62 with the shoulder 63 of the trip member.

The object of the projection 55 on the dial m plate is to effect therelease of the said trip member fromthe stop when the pro ection,

as a result of the rotation of the dial plate by the pawl 52, engagesbeneath the outer end of the said trip member and lifts it,

and the dial plate is provided with a knob 65 by means of which it maybe manually rotated to set the projection 55 in such position that itwill release the trip member 57 from its stop 62 upon the cam havingmade a predetermined number of revolutions.

' The said dial plate is preferably indexed as at 66 so that the pointer56 will show the number of revolutions required to effect thedisengagement of the trip member 57, which disengagement is accompaniedby the lifting of the test cup spindle due to the upward size of thewheels,

swinging of the arm 60 of the bell crank lever under the influence ofthe springtla, whereupon the test cup 43 is lifted out of contact withthe gllldlllg wheel.

In testing a grinding wheel it is placed upon the arbor and the arboradjusted to the test cup in the manner hereinbefore described, the tripmember 57 being lirst en gaged with the stop 62 for which purposeahandle 67 is provided, and the machine is set in operation after thedial plate has been set to provide for the number of revolutions of thespindle required. The operation of the machine then continues until suchnumber of revolutions of the spindle has been effected. the revolutionsof the grinding wheel being governed by the size of the wneel as hasalso been described; and when the pin 55 trips the trip lever 57, thetest cup 1 .3 is lifted out of contact with the grinding wheel by theaction of the spring 64.

The test cup is then measured to ascertain to what extentit has beenabraded by the grinding wheel, and the grinding wheel is also measuredto ascertain to what extent it has been worn. and as a definite numberof surface feet of the grindstone have been brought into abradingcontact with the testcup, the wear of the test cup will definitelyindicate the abrading quality of the grinding wheel, and the wear ofthegrinding wheel will indicate its wearing quality.

If another grindstone be then substituted for that previously tested andthe (.ial plate set to the previous setting, upon the completion of afurther test, the same amount of wear on the test cup is an indicationthat thesecond grinding wheel is of the same abrading quality as thepreviously'tested wheel, irrespective of any difference in the and ofcourse the wearing qualities of the wheels may be likewise compared.

It will also be apparent that uneven wear of the grindstone willmanifest itself in a noticeable rising and falling of the test cupspindle, and after the test it is quite easy to adjust the. stone sothat its lowspot is directly beneath the cup and then measure the extentto which the spindle'is raised when the high spot of the wheel isbrought beneath the cup. This will show the uneven shape or eccentricityof the stone.

The cup shaped test piece is preferably so disposed towards the abrasivewheel that its rim lies in a plane tangential to the peripheral face ofthe said 'wheel. Consequently wearing; of the test piece by the abrasivewheel does not alter the diameter of the test piece of the relativevelocities of the meetin faces of the wheel and the 1 l l) test piece.

Accordingly it is a very simple matter with a machine of this type totest large numbers of wheels and classify them as to their abrading andwearing qualities, without especial calculation for did erent sizes ofwheels, and by actual test the results attained by a machine constructedas herein described and shown are very reliable and the grading ofstones can be done much more accurately than has been possible by themethods heretofore generally adopted for that purpose.

This invention may be developed within the scope of the following claimswithout departing from the essential features of the said invention, andit is desired that the specification and drawings be read as merelyillustrative and not in a limiting sense, except as necessitated by theprior art.

What I claim is 1. In a machine for testing abrasive wheels, means forrotatably supporting an abrasive wheel, means for supporting a testpiece in contact with the periphery of said wheel, and a variable speeddriving mechanism through which the wheel supporting means is rotated,means for adjusting said mechanism according to the distance of saidtest piece from the center of said wheel, whereby said supporting meansis rotated at speeds varying inversely as the diameter of the wheel.

2. In a device of the class described, an arbor for the support of anabrasive wheel, means for supporting a test piece in contact with theperiphery of said wheel, means adjustably varying the distance betweenthe test piece support and the arbor to suit different sizes of Wheels,and a variable speed device driving said arbor, and means .for adjustingsaid device to maintain constant the linear velocity of the periphery ofsaid wheel.

3. A device according to claim 2 wherein the arbor is movable towardsthe test piece support, and the variable speed mechanism comprises adisk mounted on said arbor and a friction driving pinion towards whichthe center of said disk moves as said arbor is moved towards said testpiece support.

4. In a machine for testing abrasive wheels, means for rotating anabrasive wheel in peripheral contact with a test piece and meanscontrolled by the bodily movement of the abrasive wheel relative to thetest piece and ensuring a constant peripheral grinding speed of thewheel irrespective of its diameter.

5. In a machine for testing abrasive wheels, means for ,rotatablysupporting an abrasive wheel, means for rotating said abra sive wheel,means for supporting a test piece in contact with the periphery of saidwheel, means for maintaining constant the linear velocity of theperiphery of said wheel, means for moving said test piece to aninoperative position, and timing means in suring the actuation of saidmoving means upon the completion of a predetermined duration ofoperation of said device.

In testimony whereof I afiix my signature.

HARLEY H. LA VERCOMBE.

